Sheet feeding mechanisms



H. T. BACKHOUSE 2,753,184

SHEET FEEDING MECHANISMS Filed Aug. 13, 1952 fiatented July 3, 1956SHEET FEEDING MECHANISMS,

Headley Townsend Backhouse, Nassau, Bahamas Application August 13, 1952,Serial No. 394,103

Claims priority, application Great Britain September 3, 1951 3 Claims.(Cl. 271-60) The invention relates to sheet feeding mechanisms of thekind which are employed in conjunction with printing and like machinesoperating on single sheets of paper, card and the like and in which thesheet are fed by conveyor means onto a feed-board where registration ofeach sheet in turn is effected against front lays, usually also againstside lays, and are then taken individually to the printing or othermachine. The sheets may be conveyed to the feed-board in the form of acontinuous stream of partly overlapping sheets.

A difficulty which arises with mechanisms of the above kind is that thefront edge of the sheet which is approaching the front lays sometimesrises above the lays and passes over the lays without registration andout of the proper time. This difficulty is especially pronounced when,as is frequently desirable, the registration of the front edge of eachsheet is effected beneath the rear portion of the preceding sheet duringthe removal thereof. ln some constructions of mechanisms of the abovekind a preliminary registration of the sheets is effected by means ofpreliminary lays which move with the sheets after engagement thereby andserve to slow down the sheets before the sheets reach the front lays aswell as to effect a preliminary registration. The above-mentioneddifculty also arises with such preliminary lays.

It has already been proposed (,see British specifications Nos. 446,886and 564,322) to provide a suction gripper operating below a feed-boardand arranged to engage the front portion of each sheet as it approachesthe lays and to travel with the sheet, while holding the sheet down uponthe board, towards the lays. Such known grippers are given areciprocatory movement towards and from the lays with, in the case ofthe constructions proposed in British specification No. 446,886, arising and falling movement.

According to the present invention and with a view to reducing the abovedifliculty in a particularly simple and effective manner there isprovided beneath` the feed-board in a sheet feeding mechanism of theabove kind, a suction gripper which projects upwardly through the boardat a position to engage the front edge portion ofa sheet as itapproaches the front lays, and which is carried on one end of an arm ofwhich the effective length extends lengthwise beneath the board andwhich is supported at its other end for rocking movement about atransverse axis at a fixed position beneath the board, in combinationwith means to rock the arm about the said axis so as to raise thegripper to engage and grip the underside of each sheet before it reachesthe front lays and then to lower the gripper so as to draw the sheetdown on to the board,

Preferably the arm extends forwardly (i. e. in the direction of sheetfeed) from the aforesaid axis so that the nozzle mouth, as it moves inan arcuate path downwardly with the sheet, also has a component ofmovement in the feeding direction and tends to travel with the sheet.

The means for rocking the shaft conveniently comprise a rearwardextension of the arm from the rocking axis and an abutment carried onthe free end of an arm extending from a transverse rock-shaft beneaththe board, the abutment being given an arcuate movement as the shaftoscillates and in that movement to engage the extension aforesaid and tomove the gripper arm in one direction, the return movement beingeffected by spring means. It is also preferred that it is the movementof the gripper in the downward directionwhich is effected by the springmeans.

A further preferred feature is that valve means are incorporatedarranged to control the admission of suction to the gripper in time togrip the sheet and then, when the sheet has been drawn down on to theboard to admit air to the gripper to release the sheet.

One specific construction of a sheet feeding mechanism embodying theabove and other features will now be described by way of example of theinvention and with reference to the drawings, in which:

Figures l and 2 are side views, partly in section, showing the partsprovided by the invention in two different positions,

Figure 3 is a front View of some of the parts shown in Figure l, and

Figure 4 is a section through the gripper nozzle.

In this example the mechanism has a feed-board 11 to which the sheets 12are fed, in known manner, in the form of a continuous stream of partlyoverlapping sheets. At the front edge of the feed-board there are, inthis example, two front lays 13 which project upwardly above the surfaceof the board during registration of each sheet and are then withdrawnbelow the board to facilitate removal of the sheet. Associated with eachlay there is an auxiliary catch lay 13 or stop 14 in the form of an armwhich extends upwardly just behind the main lay i3 (in the direction offeed) and is carried by a shaft 15 below the board. The catch lay 14 hasthe upper end curved or hooked towards the advancing sheets and in usethe shaft 15 is oscillated to cause the catch lay or stop lll to travelfirst towards the advancing sheets during which time it will arrest andpre-register the leading sheet if this sheet is ahead of its propertiming, then to dwell momentarily to wait for and register the sheet ifit is properly timed or late and then to reverse and travel back pastthe main lays at about half the speed of the main sheet stream. Thetiming of the mechanism is, as shown in Figures l and 2, such that thepreliminary registration of each sheet is effected while the rearportion of the previous sheet is being removed over the top of the lays13.

l' ust behind each auxiliary catch lay 14 there is a suction gripper 16.The gripper 16 is in the form of a nozzle which may project upwardlythrough the feed-board and l is carried at the free end of a lever arm17, pivotally supported on a spindle 18 below the board 1l foroscillation about an axis transverse to the feeding direction. The leverarm 17 has a rearward extension 2U with its free end formed with a camsurface. A Second transverse shaft 21 below the board 11 carries anupwardly directed arm 22 with a roller 23 on its side at the free end.This roller 23 co-operates with the cam surface on the lever arm 17 todepress the rearward extension thereof and so to move the gripperupwardly as the roller 23 moves forwardly. The return downward movementof the gripper 16 is effected by the spring about to be described.

The spindle 18 carrying the fever arm 2.0 is supported in a bracket 2Sdependent from the board 1l and also serving as a bearing for the shaft15 carrying the auxiliary lays 14. Surrounding the spindle 1S there is acoil spring 26 which acts between a head 27 on the spindle i8 and thearm 17 to serve both as a return spring for the arm and also as acompression spring urging the arm into pressure contact with a side faceof the bracket 2S. This side face has two ports 28, 29 one above theother in front of the spindle 18. The upper port 28 is continuouslyconnected to a source of suction and the lower port 29 is connected toatmosphere. The lever arm 2l) has a single elongated port 30 which leadsthrough passageway 3l to the orifice of the suction gripper 16 and, whenthe gripper 3.6 is in its raised position (see Figure l), registers withthe suction port 28 to connect the gripper to suction and when thegripper moves down to the level of the board (see Figure 2) shuts oilthe suction and connects the gripper to atmosphere through port 29.

.lt should be appreciated that as the mouth ot the griper nozzle 16 isabove and in 'front of thc spindle i3 the mouth has a component offorward movement as the gripper nozzle le is lowered.

in use the gripper 16 is raised above the level ot the board immediatelyafter the front edge of a sheet to be registered has passed over it (seeFigure l) thereby to grip the sheet, is then lowered to draw the sheetdown on to the board 1l and to ensure that the front edge is presentedFor engagement with the auxiliary lays ld, and continues its movementbelow the surface of the hoard after suction has been cut oit.

For the purpose of providing some measure of adjustment ot the degree ofsuction at the nozzle orifice (e. g. to adjust the device for use onthin paper or on card) there may he provided in the wall of the nozzleone or more (c. g. two) holes 32 leading to the atmosphere and there maybc a short nipple 33 screwed into the nozzle for adjustment to cover oruncover the holes. The nipple 33 may be flush ywith the nozzle orificewhen the holes 32 are uncovered and below the orifice when they arecovered thus providing a double adjustment by varying the effective areaof the mouth of the nozzle and by varying the degree of effectivesuction. T he nipple may have a hexagonal section bore 34 and beadjusted by means of a hey fitting into the bore.

It is a feature of the mechanism forming the subject ot' this examplethat the length ot the path oi the sheets, between the position at whichthey cease to be positively carried by the conveyor and the position atwhich they engage the front lays, is very short. Consequently it isunnecessary to provide suction grippers or other control means whichhave substantial movement in the feeding direction as has been necessaryto carry the sheets up to thc front lays in earlier proposals where thelength ot' the path aforesaid has been long and more` than the sheetswill traverse under their momentum or without positive feed.

The front lays used in the present invention are, preferably, withoutthe cover plates or horizontally extending portions suggested in someearlier proposals and under which the. front edge portions of the sheetsare to be received immediately before registration.

When, as in the drawing, such cover plates are omitted, there may beprovided smoother bars, indicated diagrammatically at 3G, which movedownwardly after the suction gripper has released the sheet, to pressthe sheet against the board. Such smoother bars will be lowered afterthe rear end of the preceding sheet 38 has moved from under the bars andwill be raised after registration to permit removal of the sheet.

l claim:

l. A sheet feeding mechanism of the kind embodying a feed-board,conveyor means by which a succession of sheets are fed along the boardand front lays against which the leading edge of each sheet on the boardis registered in turn, characterized by an arm of fixed lengthpositioned below the fecd-board with its effective length extending inthe direction of feed of the sheets to the front lays, a suction gripperfixed to that end of the arm which is nearer to the front lays andarranged for projection upwardly through the board at a position toengage the front edge portion of a sheet as it approaches the frontlays, means for supporting the arm for rocking movement of the arm abouta transverse axis at a lixed position beneath the board, means to rochthe arm about said axis whereby the gripper is given an arcuate rockingmovement about said axis to raise the gripper above the feed-board toengage the underside of each sheet before the sheet reaches the frontlays and then to lower the gripper at least to the level of the board todraw the sheet down on to the beard, a iiXed bracket at one side of thearm, the bracket and arm being formed with surfaces which mate with oneanother as the arm rocks, spring means urging the mating faces intopressure-sealing contact, said bracket having in its mating face twoports with connections to atmosphere and to a source of suctionrespectively, said arm having in its mating face a single port with athroughway leading to the gripper, the ports being so positioned thatwhen the gripper is raised above the level of the feed-board the port'in the arms registers with the port in the bracket having the suctionconnection and when the gripper is lowered the port in the arm registerswith the port having the connection to atmosphere, whereby the gripperis opened to suction as the gripper rises above the feed-board and whenthe gripper is lowered to the level of the board the grip per is cut offfrom the suction and opened to atmosphere,

2. A sheet feeding mechanism as claimed in claim l in which the gripperis of tubular form and has a tubular insert movable axially therein froma position in which it is level with the mouth of the gripper to aposition in which it is below the said mouth.

3. A sheet feeding mechanism as claimed in claim 2 in which there is ableed hole through the tubular wall of the gripper and the insert isaxially movable to cover and uncover the said bleed hole.

References Cited in the le of this patent UNITED STATES PATENTS1,993,240 Ciolino Mar. 5, 1935 2,011,776 Reinartz Aug. 20, `l9352,087,997 Reinartz luiy 27, 1937

